Plan Agreado Estrategias Resueltas

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Aggregate Planning

M.C. Sergio No Prez Loaiza / Planeacin de la Produccin

The McGraw-Hill Companies, Inc., 2004

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Sales and Operations Planning

The Aggregate Operations Plan

Examples: Chase and Level strategies

OBJECTIVES

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Master scheduling

Material requirements planning

Order scheduling

Weekly workforce and

customer scheduling

Daily workforce and customer scheduling

Process planning

Strategic capacity planning

Sales and operations (aggregate) planning

Long

range

Intermediate

range

Short

range

Manufacturing

Services

Exhibit 13.1

Sales plan Aggregate operations plan

Forecasting

& demand

management

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Sales and Operations Planning Activities

Long-range planning Greater than one year planning horizon

Usually performed in annual increments

Medium-range planning Six to eighteen months

Usually with monthly or quarterly increments

Short-range planning One day to less than six months

Usually with weekly increments

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The Aggregate Operations Plan

Main purpose: Specify the optimal combination of production rate (units completed per unit of time)

workforce level (number of workers) inventory on hand (inventory carried from previous period)

Product group or broad category (Aggregation)

This planning is done over an intermediate-range planning period of 6 to18 months

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Balancing Aggregate Demand and Aggregate Production Capacity

0

2000

4000

6000

8000

10000

Jan Feb Mar Apr May Jun

4500 5500

7000

10000

8000

6000

0

2000

4000

6000

8000

10000

Jan Feb Mar Apr May Jun

4500 4000

9000 8000

4000

6000

Suppose the figure to

the right represents

forecast demand in

units

Now suppose this

lower figure represents

the aggregate capacity

of the company to

meet demand

What we want to do is

balance out the

production rate,

workforce levels, and

inventory to make

these figures match up

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Required Inputs to the Production Planning System

Planning

for

production

External

capacity

Competitors

behavior

Raw material

availability

Market

demand

Economic

conditions

Current

physical

capacity

Current

workforce

Inventory

levels

Activities

required

for

production

External

to firm

Internal

to firm

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Key Strategies for Meeting Demand

Chase

Level

Some combination of the two

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Aggregate Planning Examples: Unit Demand and Cost Data

Materials $5/unit

Holding costs $1/unit per mo.

Marginal cost of stockout $1.25/unit per mo.

Hiring and training cost $200/worker

Layoff costs $250/worker

Labor hours required .15 hrs/unit

Straight time labor cost $8/hour

Beginning inventory 250 units

Productive hours/worker/day 7.25

Paid straight hrs/day 8

Suppose we have the following unit

demand and cost information:

Demand/mo Jan Feb Mar Apr May Jun

4500 5500 7000 10000 8000 6000

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Jan Feb Mar Apr May Jun

Days/mo 22 19 21 21 22 20

Hrs/worker/mo 159.5 137.75 152.25 152.25 159.5 145

Units/worker 1063.33 918.33 1015 1015 1063.33 966.67

$/worker $1,408 1,216 1,344 1,344 1,408 1,280

Productive hours/worker/day 7.25

Paid straight hrs/day 8

Demand/mo Jan Feb Mar Apr May

Jun

4500 5500 7000 10000 8000

6000

Given the demand and cost information below, what

are the aggregate hours/worker/month, units/worker, and

dollars/worker?

7.25x2

2

7.25x0.15=48.33

&

84.33x22=1063.33 22x8hrsx$8=$140

8

Cut-and-Try Example: Determining Straight Labor Costs and Output

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Chase Strategy (Hiring & Firing to meet demand)

Jan

Days/mo 22

Hrs/worker/mo 159.5

Units/worker 1 ,063 .33

$/worker $1 ,408

Jan

Demand 4,500

Beg. inv. 250

Net req. 4 ,250

Req. workers 3 .997

Hired

Fired 3

W orkforce 4

Ending inventory 0

Lets assume our current workforce is 7

workers.

First, calculate net requirements for

production, or 4500-250=4250 units

Then, calculate number of workers

needed to produce the net

requirements, or

4250/1063.33=3.997 or 4 workers

Finally, determine the number of

workers to hire/fire. In this case we

only need 4 workers, we have 7, so

3 can be fired.

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Jan Feb Mar Apr May Jun

Days/mo 22 19 21 21 22 20

Hrs/worker/mo 159.5 137.75 152.25 152.25 159.5 145

Units/worker 1,063 918 1,015 1,015 1,063 967

$/worker $1,408 1,216 1,344 1,344 1,408 1,280

Jan Feb Mar Apr May Jun

Demand 4,500 5,500 7,000 10,000 8,000 6,000

Beg. inv. 250

Net req. 4,250 5,500 7,000 10,000 8,000 6,000

Req. workers 3.997 5.989 6.897 9.852 7.524 6.207

Hired 2 1 3

Fired 3 2 1

Workforce 4 6 7 10 8 7

Ending inventory 0 0 0 0 0 0

Below are the complete calculations for the remaining

months in the six month planning horizon

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Jan Feb Mar Apr May Jun

Demand 4,500 5,500 7,000 10,000 8,000 6,000

Beg. inv. 250

Net req. 4,250 5,500 7,000 10,000 8,000 6,000

Req. workers 3.997 5.989 6.897 9.852 7.524 6.207

Hired 2 1 3

Fired 3 2 1

Workforce 4 6 7 10 8 7

Ending inventory 0 0 0 0 0 0

Jan Feb Mar Apr May Jun Costs

Material $21,250.00 $27,500.00 $35,000.00 $50,000.00 $40,000.00 $30,000.00 203,750.00

Labor 5,627.59 7,282.76 9,268.97 13,241.38 10,593.10 7,944.83 53,958.62

Hiring cost 400.00 200.00 600.00 1,200.00

Firing cost 750.00 500.00 250.00 1,500.00

$260,408.62

Below are the complete calculations for the remaining months in

the six month planning horizon with the other costs included

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Level Workforce Strategy (Surplus and Shortage Allowed)

Jan

Demand 4,500

Beg. inv. 250

Net req. 4,250

W orkers 6

Production 6,380

Ending inventory 2,130

Surplus 2,130

Shortage

Lets take the same problem as

before but this time use the

Level Workforce strategy

This time we will seek to use

a workforce level of 6 workers

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Jan Feb Mar Apr May Jun

Demand 4,500 5,500 7,000 10,000 8,000 6,000

Beg. inv. 250 2,130 2,140 1,230 -2,680 -1,300

Net req. 4,250 3,370 4,860 8,770 10,680 7,300

Workers 6 6 6 6 6 6

Production 6,380 5,510 6,090 6,090 6,380 5,800

Ending inventory 2,130 2,140 1,230 -2,680 -1,300 -1,500

Surplus 2,130 2,140 1,230

Shortage 2,680 1,300 1,500

Note, if we recalculate this sheet with 7 workers

we would have a surplus

Below are the complete calculations for the remaining

months in the six month planning horizon

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Jan Feb Mar Apr May Jun

4,500 5,500 7,000 10,000 8,000 6,000

250 2,130 10 -910 -3,910 -1,620

4,250 3,370 4,860 8,770 10,680 7,300

6 6 6 6 6 6

6,380 5,510 6,090 6,090 6,380 5,800

2,130 2,140 1,230 -2,680 -1,300 -1,500

2,130 2,140 1,230

2,680 1,300 1,500

Jan Feb Mar Apr May Jun

$8,448 $7,296 $8,064 $8,064 $8,448 $7,680 $48,000.00

31,900 27,550 30,450 30,450 31,900 29,000 181,250.00

2,130 2,140 1,230 5,500.00

3,350 1,625 1,875 6,850.00

$241,600.00

Below are the complete calculations for the

remaining months in the six month planning

horizon with the other costs included

Note, total

costs under

this strategy

are less than

Chase at

$260.408.62

Labor

Material

Storage

Stockout